The influence of Sc on α/β transformation of Ti

Samples of pure Ti, Ti–2Sc, Ti–5Sc, Ti–25Sc and Ti–37Sc (wt%) were prepared by vacuum arc melting technique and examined by optical microscope (OM), X-ray diffraction (XRD), differential thermal analyzer (DTA), and hardness test. The results showed that the introduction of small amount of Sc helps refining as-cast microstructure and increases Vickers hardness from 190 HV0.01 (pure Ti) to 308 HV0.01 (Ti–2Sc). A lamellar microstructure of α was obtained in as-cast alloy. The grain size of β phase was larger than 100 μm and α lamellar nucleated at β grain boundary. The lattice constants of as-cast Ti–Sc alloys were measured by XRD method. Microstructure evolution of Ti–Sc binary alloys annealed at different temperatures was revealed by OM too. Furthermore, as β-phase stabilizer, the function of Sc was thermodynamically analyzed.